Earl Craig's Atlantis on the Blug

[Patrick Moore]

I don't want a second top tube on any bike I own because it would serve no real purpose and add needless weight (and also, perhaps, rigidity where I don't want it), but I do have to say that the curved second tube on those Atlantises looks wonderful *as sculpture.* In fact, merely aesthetically, I think that edition of the Atlantis is one of the prettiest bikes, if not the prettiest bike that Rivendell has made.

In other, and very unrelated news -- but I opened the window at the same time as I opened the Blug window -- fenders are going road-mainstream:

https://www.bikeradar.com/features/bikes-with-fender-mounts/

Patrick Moore, who would indeed install fenders on his Atlantis if he had an Atlantis.

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Patrick Moore

Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum

[Jason Fuller]

I can imagine it's useful once you get into the 60cm range, since the average rider weight is going up while the structural triangulation of the frame is going down.  But I can't deny that I love the totally unnecessary extra tube on the Hunq so who am I to judge. 

The "unnecessary tube" I want, and would put on a Riv custom if I ever got one, would be the lift handle from the Rosco's. I keep hoping for it on new models. 

[S]

Yes, the extra tube strengthens the frame. Otherwise you would be left with a wobblier triangle and have to use thicker tubes and there goes at least some of your weight savings. I think it's a good solution and looks cool, so a double win.

[Patrick Moore]

Not true at all, unless -- perhaps -- you are well over 200 lb and carry heavy loads. I owned and rode a 60 c-c frame extensively -- my best level top tube size is 60 c-c -- and there was no more flex notiher 6- X 56 c-cceable than with an 18" mountain bike frame. And this frame was made from standard gauge, and not OS, tubes.

I currently have another 60 X 56 c-c frame being refurbished; this is also standard gauge, and it is very light: 5.9 lb for frame + fork + steel Campy headset; I do not expect to need a second top tube. I'm 175.

And my best load carrier of all time, that happily and securely carried 40+ in back (on an 11 oz rack!) was made from standard gauge, lightweight 531 and was noticeably lighter than my 2003, 58 c-c Riv frame that weighed 7 lb for frame + fork and Ultegra headset. This frame was a 58 c-c, IIRC.

For anyone under say 250 lb who does not carry camping loads, a second top tube is ornamental, not structural. Amen.

Back when I lived in India and Pakistan and Kenya, you'd often see heavy duty models of the stereotypical rod brake roadster wtih a second top tube (and with heavy aftermarket fork braces), but these were bikes cheaply made from cheap, weak tubing that carried 100 lb loads of firewood or 200 lb loads of charcoal in gunny sacks, or a family of 4; even so, most Indian and Pakistani made r b roadsters have single top tubes.

Upshot: they look cool, but their benefit is purely aesthetic.

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[Mike Godwin]

My Della Santa is outfitted with drop out eyelets and threaded chainstay and brakebridge brazeons for fenders, and it is a racey bike.

Mike SLO CA

[Patrick Moore]

I'll bet it doesn't have a second top tube.

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[Mike Godwin]

No but it does have a chrome-plated contrasting paint-filled twin-plate fork crown. Does that almost count?

Mike SLO CA

On Monday, August 3, 2020 at 8:29:05 PM UTC-7, Patrick Moore wrote:

I'll bet it doesn't have a second top tube.

On Mon, Aug 3, 2020 at 9:27 PM Mike Godwin <spoke...@gmail.com> wrote:

My Della Santa is outfitted with drop out eyelets and threaded chainstay and brakebridge brazeons for fenders, and it is a racey bike.

Mike SLO CA

On Monday, August 3, 2020 at 9:00:02 AM UTC-7, Patrick Moore wrote:

I don't want a second top tube on any bike I own because it would serve no real purpose and add needless weight (and also, perhaps, rigidity where I don't want it), but I do have to say that the curved second tube on those Atlantises looks wonderful *as sculpture.* In fact, merely aesthetically, I think that edition of the Atlantis is one of the prettiest bikes, if not the prettiest bike that Rivendell has made.

In other, and very unrelated news -- but I opened the window at the same time as I opened the Blug window -- fenders are going road-mainstream:

https://www.bikeradar.com/features/bikes-with-fender-mounts/

Patrick Moore, who would indeed install fenders on his Atlantis if he had an Atlantis.

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Patrick Moore

Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum

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[Patrick Moore]

My biplane crown (new Chauncey) is racier than your biplane crown, and I'll bet the bike faster than your Della Santa -- it has an alloy shell QR SA hub. (This bike as fenders, racks f and r, lighting, but no double tt.)

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[S]

As is my habit, I overstated my case. What I said is technically true, because of physics, but I can believe the real world effect might be negligible.

In the back of my mind was the side discussion on here or iBob about the supposed deadness of the Surly Cross Check frame. Some forum members -- me included -- insisted the frame was a dog, no question, while others disagreed. As it turned out, those in the former camp had the 56 and those in the latter camp larger sizes. The theory was floated that maybe the frame "opens up," that is, flexes more, in a good way, in the larger sizes -- and with generally heavier riders -- and that accounted for the difference. To me, this seems plausible. And if it's plausible that a frame could improve in this way, then it also seems plausible that, conversely, some frames could open up *too much* and become too flexy, in larger sizes, thus necessitating some modification to maintain the same relative stiffness as in the smaller sizes.

Also in the back of my mind was the experience of my larger cycling friends who seem to break more frames than I ever have. But then, that's anecdotal.

I don't know if Grant ran any numbers or did any testing before deciding to add the second tube to some bikes. Could just be for looks, or could be a belt and suspenders kind of thing. Or a mix. But I wouldn't say it's totally off base from an engineering point of view.

Anyway, you've ridden more 60 (and maybe 60 plus?) size frames than I have, and if you say you don't feel a difference, then I can't argue.

[Steve Palincsar]

https://www.youtube.com/watch?v=WO23WBji_Z0

On 8/3/20 11:37 PM, Patrick Moore wrote:

My biplane crown (new Chauncey) is racier than your biplane crown, and I'll bet the bike faster than your Della Santa -- it has an alloy shell QR SA hub. (This bike as fenders, racks f and r, lighting, but no double tt.)

On Mon, Aug 3, 2020 at 9:34 PM Mike Godwin <spoke...@gmail.com> wrote:

No but it does have a chrome-plated contrasting paint-filled twin-plate fork crown. Does that almost count?

Mike SLO CA

On Monday, August 3, 2020 at 8:29:05 PM UTC-7, Patrick Moore wrote:

I'll bet it doesn't have a second top tube.

On Mon, Aug 3, 2020 at 9:27 PM Mike Godwin <spoke...@gmail.com> wrote:

My Della Santa is outfitted with drop out eyelets and threaded chainstay and brakebridge brazeons for fenders, and it is a racey bike.

Mike SLO CA

On Monday, August 3, 2020 at 9:00:02 AM UTC-7, Patrick Moore wrote:

I don't want a second top tube on any bike I own because it would serve no real purpose and add needless weight (and also, perhaps, rigidity where I don't want it), but I do have to say that the curved second tube on those Atlantises looks wonderful *as sculpture.* In fact, merely aesthetically, I think that edition of the Atlantis is one of the prettiest bikes, if not the prettiest bike that Rivendell has made.

In other, and very unrelated news -- but I opened the window at the same time as I opened the Blug window -- fenders are going road-mainstream:

https://www.bikeradar.com/features/bikes-with-fender-mounts/

Patrick Moore, who would indeed install fenders on his Atlantis if he had an Atlantis.

-- 
Steve Palincsar
Alexandria, Virginia 
USA

[tuolumne bikes]

Patrick has set (ok tied) a new record for drifting off topic--original post!

[Patrick Moore]

You are right that a second top tube will do something structurally; there's no avoiding that, and I overstated my own case. But my point is that for anything but a very large frame, or for a frame to be ridden by someone exceptionally heavy, there's no **practical** purposes served by the added tube.

Still, that Atlantis frame does look very pretty; far nicer IMO than the other models with 2 top tubes; they got the mix of straight and curved just right.

To view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/37f7aaa9-adbd-4329-bf5c-eab5cba24d9en%40googlegroups.com.

[ted]

Unless nobody ever looks at it, I'd argue that improving aesthetics **is** a practical purpose.

I also suspect that in many situations an extra 1/2 lb in the total bike + rider + stuff (e.g. bags, tools, spares, cloths, water, food, etc) weight is imperceptible, and therefore not a practical (as opposed to theoretical) detriment.

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[Robert Tilley]

Even a large frame for heavy rider doesn't need an additional top tube. Check out Shaq's bike here. It does have beefier tubing though per the article. Bill Walton rides around here on a pretty normal bike as well. 

https://www.bicycling.com/news/a20050684/shaqs-new-custom-bike-is-huge-and-totally-awesome/

Robert Tilley

San Diego, CA

Sent from my BlackBerry - the most secure mobile device

From: bert...@gmail.com Sent: August 4, 2020 6:58 AM To: rbw-owne...@googlegroups.com Reply-to: rbw-owne...@googlegroups.com Subject: Re: [RBW] Re: Earl Craig's Atlantis on the Blug

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Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum

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[Patrick Moore]

Compact frame, though. And it has fork braces! I used to see those on old rod braked roadsters: some clearly garage-industry blacksmith work made from crude steel rods, some more sophisticated, chromed and with heavy, chromed springs at the handlebar clamps. One wonders if the springs were the aesthetic equivalent of dual top tubes on 56 cm frames.

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Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum

[Ryan M.]

I sometimes wish I were y’all enough to have a double top tube bike, but I’m short and always ride small bikes. Oh well...they do look nice to me.

[Patrick Moore]

Improving aesthetics meets an aesthetic need.

Sure, another 12 oz won't make a practical difference on a heavy bike, but the point is, there's not practical reason for it, with the qualifications already described. It's like adding a 12 oz mascot made of chromed steel to a specially braced front fender: aesthetics only. One can wear a 1 lb weight around one's waist; no practical difference, but there's certainly no structural reason for doing so.

On Tue, Aug 4, 2020 at 10:09 AM ted <ted....@comcast.net> wrote:

Unless nobody ever looks at it, I'd argue that improving aesthetics **is** a practical purpose.

I also suspect that in many situations an extra 1/2 lb in the total bike + rider + stuff (e.g. bags, tools, spares, cloths, water, food, etc) weight is imperceptible, and therefore not a practical (as opposed to theoretical) detriment.

[Patrick Moore]

No argument as far as the Atlantis goes.

On Tue, Aug 4, 2020 at 11:10 AM Ryan M. <ryan.merri...@gmail.com> wrote:

I sometimes wish I were y’all enough to have a double top tube bike, but I’m short and always ride small bikes. Oh well...they do look nice to me.

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[S]

Mostly, it’s interesting to me that in going from an 18” (46cm) mountain bike frame to a 60cm frame there is apparently no need to make any design changes for the sake of rigidity. Or that, in this area, tubing gauge is much more important. I suppose I have been way overestimating how much bike frames flex. Does this mean smaller frames tend to be overbuilt? Does it have any implications for “planing”? I don’t know.

[ted]

The point is, looking good is a practical reason for it. Furthermore you don't seem to feel there is a practical reason for that tube not to be there on that bike, but you do seem to feel its existence should be justified by some non aesthetic motivation/rational. That seems sort of arbitrary and unfair to me. Like placing a burden of proof where it does not belong.

"Improving aesthetics meets an aesthetic need." is pretty much a tautology and as such is basically meaningless.

Do you intend to suggest that aesthetics are by definition not practical? If yes I disagree.

Lets see, "practical", i.e. good in actual (real world) practice/use as opposed to say hypothetical, theoretical, or even measurable but insignificant. I don't think practical is a synonym for structural. Nor are aesthetic and practical antonyms.

Saying aesthetics are not a practical concern implies nobody looks at the thing in question, or just nobody cares what it looks like. The appearance of my bikes is a practical concern for me (i.e. I care what they look like). YMMV.

Saying some feature is aesthetic but impractical would normally imply that the feature (though it looks nice) causes some discomfort, or inconvenience, or impairs some core function, when the thing is actually used. I don't see the practical down side of the rainbow tube on the bike in the blug, unless one doesn't like the look of it. (Well maybe it might get in the way of getting that tall hydroflask in or out of the cage on the down tube.) So I don't think it would be right to call that tube "impractical". If it's not impractical, it would seem odd to charge it with lacking a practical reason for being.

qed ish

ted, who when asked about the reasoning behind the extra top tube on his 52 bombadil replied "it's a gratuitous excuse for more fancy lug work", or something like that.

[Patrick Moore]

Ted, it's not rocket science. The tube looks good (on this bike) but serves no real, practical need.

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[brendonoid]

Both of my Double TT Rivs have wobbly steel around the seat lug from overheating the tubes during brazing. I would think this alone would undo any strength gains from a second tube but what do I know. With that said my 60cm Sam with double TT holds the same load on racks as the Single TT Homer with much less flex. So yeah it is noticable in that scenario. 

Riv tests its frames and Grant would have the math on this? I would think? *shrug*

Making my post vaguely on topic. In 2018 when the new Atlanti came out I found the 59 Atlantis extremely handsome but bought one of the remaining 58 Appa's instead because after some of Grants Blahgs at the time I thought that the Appaloosa would probably be the last FULLY LUGGED Rivendell ever made. Sometimes I regret my decision. But not really. That Atlantis Headbadge is still one of my favourites.

[EricP]

Well, I'm definitely heavy enough where the second top tube on my Sam Hillborne should make a difference. Does it? I dunno. But after this many years am used to it. Always felt it was as much marketing to be different than Surly, All City and some other brands. It does ride well and has been my only bike for a bit. At least until my Clem shows up.

My only complaint with this bike is the brakes. If I had known they were going to cantilever frames might have waited. Even with good pads set up well, not overly happy with the side pulls. But that's my preference, not a slam against the design.

Eric Platt
St. Paul, MN

[Mark Roland]

Please explain what "wobbly steel" is, and how one identifies it?

I would guess that, in frames smaller than, I don't know, 62cm, a second top tube will not have much affect on how the bike handles or carries a load. Especially since Rivendells use fairly beefy tubing to begin with. From my point of view, I see it as much as an extension of Just Ride as anything else. Traditional bicycle design with steel hasn't strayed much lately from the basic diamond frame. Why be so darn serious all the time?

In the first bike boom of the late 1800s, there was more variation, including double top tubes. I think in addition to being an aesthetic choice, and nominally a structural one in the largest frames,  it visually signals one of the companies credos:

The kind of bikes we don’t do:

We don’t “do” racing bikes; not road, not mountain, not gravel. We make bikes for daily riders, tourers, commuters, shoppers, trail riders. For athletes and get-arounders. Not for racers. Racing has tweaked and refined the comfort, safety, and versatility out of bicycles, and on the way, it has made the modern bikes into sleek and mean, dark and fat road bikes and mechanically overkilled mountain bikes.

There is no mistaking a bicycle with a double top tube for a racing machine.

[S]

On Wednesday, August 5, 2020 at 2:27:30 AM UTC-7 brendonoid wrote:

Riv tests its frames and Grant would have the math on this? I would think? *shrug*

No need to be snarky. I know Riv tests their frames and that they pass the strictest test for mountain frames. My point was, I don't know if, in the specific case of adding a second top tube, Grant based his decision on an actual test, or engineering numbers -- that is, did he run some kind of defection test, see that the larger frames were flexing significantly more than smaller frames and only then decide to add the second top tube to these larger frames? I doubt it, which isn't to say he made a bad decision, I just have no evidence he added the second tube to solve a serious, known problem. That's fine. I think it hurts nothing and looks cool. 

[S]

Should read "deflection," not "defection."

[Patrick Moore]

More reflection on this particular aspect of the thread. I will first be more clear about my assertion, which is simply that such double top tubes as we are talking about provide aesthetic and not practically beneficial structural benefits.

I will add that, far from being negligible, aesthetics -- or to use a simpler, more concrete, and more significant word, beauty -- is an essential part of a good life, and this extends to everyday artifacts. Thus I would say, to clarify, that aesthetics -- or looks, or, in a word, beauty -- is important; it just does't add a structural benefit.

Make sense?

On Tue, Aug 4, 2020 at 10:09 AM ted <ted....@comcast.net> wrote:

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[Jason Fuller]

I have a Soma Grand Randonneur, and I would say that's "wobbly steel" - you can visually see the bottom bracket swing from side to side relative to the head tube when you're putting even moderate power through the drivetrain. 

Couple notes on the aesthetics of "unnecessary tubes"

- The beauty of a bicycle is a personal blend of its artistic beauty and its functional (machine) quality, and we all lean different ways. 

- Beauty is, of course, HIGHLY subjective and a huge number of people think that a modern, aero road bike looks better than a clunky ol' Rivendell. I know, it pains you to think that's true, but it's definitely true. 

I wouldn't want a tube that's truly unnecessary except for appearance, but I don't think such a tube exists - it's always going to have some effect on the overall stiffness / response of the frame, and it often comes with neat things like additional water bottle cages or options for bags, etc. 

[Patrick Moore]

As to the structural effects of double top tubes: Sure, any such member will make a difference to the behavior of the frame; the question is whether this effect serves any useful purpose for the rider. And besides the question of whether such effects are necessary, there is also the question of whether added stiffness makes for too much stiffness. I have learned over the last couple of months that my 2003 Riv custom was in fact too stiff for me, or at least, stiff in a way that didn't work for me, compared to the new, less-stiff or differently-stiff frame.

As to the question of aesthetics, I disagree that beauty is entirely subjective, leaving out the separate question of personal affinities; if it were, the term would have no meaning; but we all experience something we can identify as beauty, whether or not we can define it in words, and we mean something when we talk about it; we're not just making empty sounds. But that's another question.

On Wed, Aug 5, 2020 at 12:14 PM Jason Fuller <jtf.f...@gmail.com> wrote:

...I wouldn't want a tube that's truly unnecessary except for appearance, but I don't think such a tube exists - it's always going to have some effect on the overall stiffness / response of the frame, and it often comes with neat things like additional water bottle cages or options for bags, etc. 

[Sean Keesler]

I have a 2tt Sam that I am taking out for long staycation tours of my area. I didn't notice the extra ounces of the 2nd tube over a 300k last weekend, but did appreciate the comments about the bike when I stopped for supplies. It added to my day and the overall pleasure of owning and riding the bike...the novelty of it was the feature that drew me to it.

[R Olson]

I'm 260 lbs and own a double TT Appa 58cm, 61 cm Roadeo, 64cm Clem L and 59cm Clem L (the clem's are for other family members, but I've ridden them).  Here's the order from most flexy to least:

1) 64 cm Clem L

2) 59 cm Clem L

3) Roadeo

4) Appa

No surprise there, but the difference between 2 and 3 is substantial, and the diff between 3 and 4 isn't very much at all.  Have also owned a 62 cm double TT Appa (1st Gen), which was flexier than the Roadeo.  Not sure if the Roadeo is made from the stiffer air-hardened steel variety.  FWIW, the Roadeo feels good, doesn't feel wobbly or like it's going to break or anything. 

[Vincent Tamer]

The whole point of the Atlantis is that it is meant for loaded touring. The second tube goes on the bikes for taller riders who are presumably heavier. That along with a heavy touring load makes the extra tube a good idea.

[Steve Palincsar]

And yet, the original Atlantis was also meant for loaded touring, performed splendidly in that role, and lacked the second top tube in all sizes.

To view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/8be92e52-e605-4a40-9f2b-e17c3af5aa7an%40googlegroups.com.

[Patrick Moore]

Right on. And again: Not loaded touring, but the best rear load carrier I've owned out of dozens of bikes was that light-framed, standard-gauge, tout 531 1973 Motobecane racing bike, size 58 c-c -- and no double tt, either (tho' it did have French or Swiss -- forget -- bb threading -- right hand on drive side).

And, I've watched the Atlantis since it's inception, and it has not been sold solely as a loaded touring bike by any means; ditto for the Sam Hill.

To view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/c14d2c04-6034-2ddd-8fd6-8cf3d40b9894%40his.com.

[Michael Williams]

Whoa.  The order of flexiness from most to least really surprised me.  It’s hard to imagine a double tuber 62cm Joe being more flexy than a Roadeo and hard to imagine both Clem’s being flexier than the Roadeo.   

Sent from my iPhone

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[Bones]

When I pick up my 2TT Sam or Joe (which is frequent, going up and down stairs), I don’t have to worry about knocking my frame pump off. Also, it’s easier to work on them in my repair stand, as I can clamp on to the lower tube without interfering with the rear brake line.

Bones

[Ryan M.]

I had a Roadeo, I believe it was a 53, and never thought it was a flexy bike...More like stiff in a good way. I thought it was a really good fast road bike.

[ted]

I think the GBW is the stoutest rough stuff loaded camping bike RBW makes, and no double top tubes there.

So clearly RBW doesn't think twin top tubes or diagatubes or rainbow tubes are the only way to make a large frame with the strength / stiffness they want in a touring bike.

For some of the frames they choose to go the extra tube route to get the strength / stiffness they want for that model in that size (I presume).

To my eye the MIT Atlantis is a complete redesign, longer chain stays, more tt slope, who knows what all else is altered from the original.

I wouldn't be surprised if the existence of the extra tube influenced the choice of tubing specs.

It may be overly simplistic to assume that all things are equal except for the addition of a whole nother tube.

It seems possible that the presence (or absence) of an extra tube on a particular model and size of RBW frame tells less about its mechanical properties than some of us tend to think.

If I were in the market for a frame for the uses RBW recommends the Atlantis for, and was tall enough to ride one with a rainbow tube, I wouldn't be second guessing Grant about that tube being an appropriate design choice unless I disliked the way it looks. YMMV of course.

[brendonoid]

Sorry that you read that as snarky as It was intended in the complete opposite direction. I meant that everyone has opinions especially on this topic but the only one who actually has the math or the engineering report or whatever they get from the destructive testing of their frames is Grant Petersen. Just like you I always assumed that it was aesthetic choice and happen to fit the size frames that have double top tubes so also have personal experience riding them.

WOBBLY STEEL: The steel has a deformed surface like a melted candle. The steel has melted from being overheated because of too many joints and too much heat in a concentrated location. I always thought but do not know for sure that it is possible to reverse the annealling benefits of expensive steels during welding/brazing. I am trying to be clear here in text and not snarky.

[Mark Roland]

That would probably fall under not good, both in the aesthetic department and the not ideal for the integrity of the steel department. Are you certain it is not a bit of sloppy brazing, or a paint mishap? Can you post a photo of the wobbly area?

While you can certainly overheat a tube when brazing or welding, and that can affect the tubing to a degree, depending on what kind it is, I don't think the heat would be enough to deform the surface in the manner you describe. I could be wrong.

[Paul M]

From RBW website Grant says this about the Atlantis frame, "Quirk: The 59cm and 62cm have "rainbow" tubes that add style and structure by triangulation, and a better lifting tube than a standard top tube." For me that means aesthetics and practicality.

[S]

No worries. I apologize for mistaking your tone. As Paul M found from the Grant quote, the reasons seem to be a mix of aesthetics and function. My guess is looks came first and possible practical advantages were deduced later.

In other words, to fit a second tube at all, a frame has to be larger, whatever the reason for adding it. I think that may have more to do with the choice than a theoretical increase in stiffness or being able to use it as a carrying handle, etc.

[R Olson]

I think frame size has a lot to do with it, with or without 2 TT. I bet the main triangle size - the area from the lower top tube to the downtube and seat tube on the 62 Joe was bigger than the Roadeo, not to mention the longer chainstays. Tires too. 62 Joe had 50mm Big Apples. I think the forks on those 1st Gen Joe's weren't as stout either. Of all of them, that was the best riding bike, almost perfect responsiveness/flex for me. I only got rid of it because it was too tight in the crotch. That order was just based on my feel riding the bikes on the same routes with he same level of effort. Nothing scientific, I didn't measure deflections or anything and others may feel different if they've ridden them too. I will say the Clem's are definitely more flexy than the Roadeo though. No question on that in my mind. Not in a bad way though; still strong, capable bikes. All the bikes are fun to ride. The Roadeo is extremely responsive, responds instantly to pedal input, reminds me of stiffer aluminum road bikes that I've had in the past in terms of responsiveness, but more compliant and comfortable.

[Earl Craig]

It's been interesting reading through these comments.  This last bit here, regarding the "lift tube," caught my attention.  I LOVE this lift-tube function.  When carrying the bike up some stairs, or lifting it over an obstacle in road or trail, it great.  Keeps my pump out of harm's way, and easier on the shoulder.  And I bet this rainbow tube weighs less than 8 ounces.  Maybe Grant could answer this question.